The current study examined the effectiveness of the Prevention and Relationship Enhancement Program (PREP) with lower-income and racial/ethnic minority (African American and Latino/a) couples. Additionally, we tested whether relationship outcomes varied based on the delivery format (i.e., group format vs. couple format). The sample included 321 unmarried couples expecting a child or who have a child 3 month old or younger. The couples participated in 16 hr of PREP via a group or a couple format over the course of 2–3 months. Couples relationship quality was assessed prior to and directly after the program. The results showed that men and women demonstrated significant gains in their communication skills, relationship functioning, friendship, dedication, and relationship confidence. Couples who participated in PREP via the couple format had better outcomes on three of the seven relational outcomes as compared to couples who participated in PREP via the group format.